This invention relates to a link rod linking a body frame of an automobile and a member suspended therefrom.
In an automobile construction supporting a member for holding and bearing thereon an engine, transmission and related components, it is a well-known practice to connect the member at a front side thereof to a body frame through a link rod thus supporting the member in a suspended manner. The link rod is attached at the one end to the body frame through a rubber bush and at another end to the member through the rubber bush.
As exemplified in the accompanying FIGS. 12 to 15, a conventional link rod 101 of this kind is made of a metal pipe material and is constructed of a main rod section 102 which is fashioned by flattening working into a flattened shape generally of an ellipsoid in cross-section and of both terminal parts each flattened more so as to form a double superposed plate, in which the one terminal part is formed by being bent squarely to the elongate direction of the rod into a first attachment section 110 having an attachment hole 111 for fitting a bush at its center. The other terminal part is formed as a second attachment section 120 having an attachment hole 121 for fitting the bush, the second attachment section having an axial center in a direction intersecting an axial center of the first attachment section at an eccentric position. These attachment sections are mounted respectively to either of the body frame and the member, for instance, the first attachment section 110 is mounted to the body frame and the second attachment section 120 to the member.
In such case where the link rod is installed to the body frame and the member through the rubber bush as stated above, however, the link rod itself can cause a resonance vibration to the vibration of the member, which leads to a vibration or vibratory movement of the vehicle and generation of noise.
As a consequence, it is necessary to preliminarily set a mass, spring rate, and natural frequency value of the link rod while retaining a predetermined strength so that satisfactory vibration insulation characteristics can be obtained. Yet with the existing link rod made of a pipe material, the fabrication and working associated therewith are not easily accomplished and involve a high cost. Moreover, there is no design freedom, and as such, it is difficult to alter, control, etc. the mass and spring rate, and additionally, it is not easy to set the inherent value.
In view of the prior art problems above, it is the object of the invention to provide a link rod for connecting a body frame of an automobile and a member suspended therefrom, which is permits facilitated fabrication and allows the strength and mass to be readily adjusted, and further to optionally set the natural frequency value.
Briefly stated, the invention relates to a link rod comprising a main rod section extending vertically in the form of a plate of a required width; a first attachment section extending to form a bend portion by bending from one end of the main rod section toward the extending direction of the rod and having an attachment hole with a vertical axis center defined in the nearly central part thereof, and a second attachment section extending-contiguously to the other end of the main rod section and having an attachment hole with an axis center in a direction intersecting an axis center of the first attachment section. The invention is characterized in that the link rod is press formed of a metal plate material in a one-piece body; and the main rod section is formed, at both side edges thereof, with reinforcing flanges, the reinforcing flanges being configured in a bend form to extend contiguously at least to the location of the bend portion at the proximal end of the first attachment section. Here, it is preferred that the reinforcing flanges be configured in a bend form on the side of the first attachment section so as to extend contiguously to and alongside of the first attachment section.
According to the link rod above, it is possible to fabricate same by press forming in contrast to the case of working from a pipe material. Additionally, the reinforcing flanges, which the main rod section has at both lateral edges thereof, permit to the link rod to maintain a sufficient strength notwithstanding the plate material. More particularly, because the flanges are formed to extend contiguously from the main rod section at least to the end of the bend portion at the first attachment section, the retention of the strength at the bend portion is secured, thus permitting the link rod to maintain a predetermined spring rate. In particular, where the flanges are formed to extend contiguously to the first attachment section, it is possible to further reinforce the first attachment section together with the bend portion.
Further, owing to the press-forming working from a plate material, boring work or alteration in thickness of the plate and height of the flanges is facilitated; the strength and mass are easily adjustable; and it is possible to determine easily the spring rate by a model analysis, so that setting of the natural frequency value is also facilitated.
In the aforementioned link rod, where the reinforcing flanges have, at the bend portion from the main rod section toward the first attachment section, extension edges bent outwardly, it is possible to reinforce more effectively the bend portion, on which stress is most liable to concentrate.
In addition, in a preferred embodiment of the aforementioned link rod in which the attachment holes of the first and the second attachment sections are formed at their peripheral edges with cylindrical projections, the rubber bush can be fitted and fastened most stably, rendering the mounting state stable. Additionally, the cylindrical projections serve to strengthen the attachment sections of the plate form.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings.